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<h1>timer.c</h1><a href="timer_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/*********************************************************************************</span>
<a name="l00002"></a>00002 <span class="comment"></span>
<a name="l00003"></a>00003 <span class="comment"> Copyright 2006 MakingThings</span>
<a name="l00004"></a>00004 <span class="comment"></span>
<a name="l00005"></a>00005 <span class="comment"> Licensed under the Apache License, </span>
<a name="l00006"></a>00006 <span class="comment"> Version 2.0 (the "License"); you may not use this file except in compliance </span>
<a name="l00007"></a>00007 <span class="comment"> with the License. You may obtain a copy of the License at</span>
<a name="l00008"></a>00008 <span class="comment"></span>
<a name="l00009"></a>00009 <span class="comment"> http://www.apache.org/licenses/LICENSE-2.0 </span>
<a name="l00010"></a>00010 <span class="comment"> </span>
<a name="l00011"></a>00011 <span class="comment"> Unless required by applicable law or agreed to in writing, software distributed</span>
<a name="l00012"></a>00012 <span class="comment"> under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR</span>
<a name="l00013"></a>00013 <span class="comment"> CONDITIONS OF ANY KIND, either express or implied. See the License for</span>
<a name="l00014"></a>00014 <span class="comment"> the specific language governing permissions and limitations under the License.</span>
<a name="l00015"></a>00015 <span class="comment"></span>
<a name="l00016"></a>00016 <span class="comment">*********************************************************************************/</span>
<a name="l00017"></a>00017 <span class="comment"></span>
<a name="l00018"></a>00018 <span class="comment">/** \file timer.c </span>
<a name="l00019"></a>00019 <span class="comment">  Functions to use the timer on the Make Controller Board.</span>
<a name="l00020"></a>00020 <span class="comment">  This uses the regular interrupt mechanism and as such may be blocked by other</span>
<a name="l00021"></a>00021 <span class="comment">  routines for significant numbers of milliseconds. </span>
<a name="l00022"></a>00022 <span class="comment">*/</span>
<a name="l00023"></a>00023 
<a name="l00024"></a>00024 <span class="preprocessor">#include "AT91SAM7X256.h"</span>
<a name="l00025"></a>00025 <span class="preprocessor">#include "types.h"</span>
<a name="l00026"></a>00026 <span class="preprocessor">#include "timer.h"</span>
<a name="l00027"></a>00027 <span class="preprocessor">#include "timer_internal.h"</span>
<a name="l00028"></a>00028 <span class="preprocessor">#include "config.h"</span>
<a name="l00029"></a>00029 <span class="preprocessor">#include "rtos.h"</span>
<a name="l00030"></a>00030 
<a name="l00031"></a>00031 <span class="preprocessor">#define TIMER_CYCLES_PER_MS 48</span>
<a name="l00032"></a>00032 <span class="preprocessor"></span>
<a name="l00033"></a>00033 <span class="keyword">struct </span>Timer_ Timer;
<a name="l00034"></a>00034 
<a name="l00035"></a>00035 <span class="keyword">static</span> <span class="keywordtype">int</span> Timer_Init( <span class="keywordtype">void</span> );
<a name="l00036"></a>00036 <span class="keyword">static</span> <span class="keywordtype">int</span> Timer_Deinit( <span class="keywordtype">void</span> );
<a name="l00037"></a>00037 <span class="keyword">static</span> <span class="keywordtype">int</span> Timer_GetCount( <span class="keywordtype">void</span> );
<a name="l00038"></a>00038 <span class="keyword">static</span> <span class="keywordtype">int</span> Timer_GetTimeTarget( <span class="keywordtype">void</span> );
<a name="l00039"></a>00039 <span class="keyword">static</span> <span class="keywordtype">int</span> Timer_GetTime( <span class="keywordtype">void</span> );
<a name="l00040"></a>00040 <span class="keyword">static</span> <span class="keywordtype">void</span> Timer_SetTimeTarget( <span class="keywordtype">int</span> );
<a name="l00041"></a>00041 <span class="keyword">static</span> <span class="keywordtype">void</span> Timer_Enable( <span class="keywordtype">void</span> );
<a name="l00042"></a>00042 
<a name="l00043"></a>00043 <span class="keywordtype">void</span> Timer_Isr( <span class="keywordtype">void</span> );
<a name="l00044"></a>00044 <span class="comment"></span>
<a name="l00045"></a>00045 <span class="comment">/** \defgroup Timer</span>
<a name="l00046"></a>00046 <span class="comment">* The Timer subsystem provides a timer in a millisecond timeframe.</span>
<a name="l00047"></a>00047 <span class="comment">  For higher resolution timing, check the \ref FastTimer</span>
<a name="l00048"></a>00048 <span class="comment"></span>
<a name="l00049"></a>00049 <span class="comment">  The Timer subsystem is based on a collection of \b TimerEntries.  To start a new timer, create a new</span>
<a name="l00050"></a>00050 <span class="comment">  \b TimerEntry structure, initialize it with Timer_InitializeEntry( ), and start it with Timer_Set( ).</span>
<a name="l00051"></a>00051 <span class="comment"></span>
<a name="l00052"></a>00052 <span class="comment">  There are currently a couple of limitations to the Timer system:</span>
<a name="l00053"></a>00053 <span class="comment">  - In your callback function, you must not sleep or make any FreeRTOS-related calls.</span>
<a name="l00054"></a>00054 <span class="comment">  - To modify an existing TimerEntry, you must cancel the timer with Timer_Cancel( ), and reinitialize the TimerEntry.</span>
<a name="l00055"></a>00055 <span class="comment"></span>
<a name="l00056"></a>00056 <span class="comment">  \todo Allow the timer callbacks to cooperate with the \ref RTOS</span>
<a name="l00057"></a>00057 <span class="comment">  \todo Allow existing timer entries to be modified (repeat or not, modify the period, etc.)</span>
<a name="l00058"></a>00058 <span class="comment">* \ingroup Controller</span>
<a name="l00059"></a>00059 <span class="comment">* @{</span>
<a name="l00060"></a>00060 <span class="comment">*/</span>
<a name="l00061"></a>00061 <span class="comment"></span>
<a name="l00062"></a>00062 <span class="comment">/** </span>
<a name="l00063"></a>00063 <span class="comment">  Controls the active state of the \b Timer subsystem</span>
<a name="l00064"></a>00064 <span class="comment">  @param active whether this subsystem is active or not</span>
<a name="l00065"></a>00065 <span class="comment">  @return Zero on success.</span>
<a name="l00066"></a>00066 <span class="comment">  @see Timer_Set, Timer_Cancel</span>
<a name="l00067"></a>00067 <span class="comment">*/</span>
<a name="l00068"></a><a class="code" href="group___timer.html#g0ba988a1ac434ac70c17dfc239644dfe">00068</a> <span class="keywordtype">int</span> <a class="code" href="group___timer.html#g0ba988a1ac434ac70c17dfc239644dfe" title="Controls the active state of the Timer subsystem.">Timer_SetActive</a>( <span class="keywordtype">bool</span> active )
<a name="l00069"></a>00069 {
<a name="l00070"></a>00070   <span class="keywordflow">if</span> ( active )
<a name="l00071"></a>00071   {
<a name="l00072"></a>00072     <span class="keywordflow">if</span> ( Timer.users++ == 0 )
<a name="l00073"></a>00073     {
<a name="l00074"></a>00074       <span class="keywordtype">int</span> status;
<a name="l00075"></a>00075   
<a name="l00076"></a>00076       status = Timer_Init();  
<a name="l00077"></a>00077       <span class="keywordflow">if</span> ( status != <a class="code" href="group___error.html#gaa42bc036fbba18487ae9a15cd1f2f94" title="All&amp;#39;s well here.">CONTROLLER_OK</a> )
<a name="l00078"></a>00078       {
<a name="l00079"></a>00079         Timer.users--;
<a name="l00080"></a>00080         <span class="keywordflow">return</span> status;
<a name="l00081"></a>00081       }
<a name="l00082"></a>00082     }
<a name="l00083"></a>00083   }
<a name="l00084"></a>00084   <span class="keywordflow">else</span>
<a name="l00085"></a>00085   {
<a name="l00086"></a>00086     <span class="keywordflow">if</span> ( --Timer.users == 0 )
<a name="l00087"></a>00087       Timer_Deinit();
<a name="l00088"></a>00088   }
<a name="l00089"></a>00089   <span class="keywordflow">return</span> <a class="code" href="group___error.html#gaa42bc036fbba18487ae9a15cd1f2f94" title="All&amp;#39;s well here.">CONTROLLER_OK</a>;
<a name="l00090"></a>00090 }
<a name="l00091"></a>00091 <span class="comment"></span>
<a name="l00092"></a>00092 <span class="comment">/** </span>
<a name="l00093"></a>00093 <span class="comment">  Returns whether the timer subsystem is active or not</span>
<a name="l00094"></a>00094 <span class="comment">  @return active.</span>
<a name="l00095"></a>00095 <span class="comment">  @see Timer_Set, Timer_Cancel</span>
<a name="l00096"></a>00096 <span class="comment">*/</span>
<a name="l00097"></a><a class="code" href="group___timer.html#gbefcf81004fa679f113c0f364d9fca49">00097</a> <span class="keywordtype">int</span> <a class="code" href="group___timer.html#gbefcf81004fa679f113c0f364d9fca49" title="Returns whether the timer subsystem is active or not.">Timer_GetActive</a>( )
<a name="l00098"></a>00098 {
<a name="l00099"></a>00099   <span class="keywordflow">return</span> Timer.users &gt; 0;
<a name="l00100"></a>00100 }
<a name="l00101"></a>00101 <span class="comment"></span>
<a name="l00102"></a>00102 <span class="comment">/** </span>
<a name="l00103"></a>00103 <span class="comment">  Initializes a new timer structure.  </span>
<a name="l00104"></a>00104 <span class="comment">  The event is signified by a callback to the function provided, after the interval specified.  </span>
<a name="l00105"></a>00105 <span class="comment">  The specified ID is passed back to the function to permit one function to work for many events.  </span>
<a name="l00106"></a>00106 <span class="comment">  Pass repeat = true to make the event continue to create callbacks until it is canceled.</span>
<a name="l00107"></a>00107 <span class="comment">  @param timerEntry pointer to the TimerEntry to be intialized. </span>
<a name="l00108"></a>00108 <span class="comment">  @param timerCallback pointer to the callback function.  The function must</span>
<a name="l00109"></a>00109 <span class="comment">         be of the form \verbatim void timerCallback( int id )\endverbatim</span>
<a name="l00110"></a>00110 <span class="comment">  @param id An integer specifying the ID the callback function is to be provided with.</span>
<a name="l00111"></a>00111 <span class="comment">  @param timeMs The time in milliseconds desired for the callback.</span>
<a name="l00112"></a>00112 <span class="comment">  @param repeat Set whether the timer repeats or is a one-time event.</span>
<a name="l00113"></a>00113 <span class="comment">  @see Timer_Cancel</span>
<a name="l00114"></a>00114 <span class="comment"></span>
<a name="l00115"></a>00115 <span class="comment">  \par Example</span>
<a name="l00116"></a>00116 <span class="comment">  \code</span>
<a name="l00117"></a>00117 <span class="comment">  TimerEntry myTimer; // our TimerEntry</span>
<a name="l00118"></a>00118 <span class="comment">  Timer_InitializeEntry( &amp;myTimer, myCallback, 0, 250, true );</span>
<a name="l00119"></a>00119 <span class="comment">  Timer_Set( &amp;myTimer ); // start our timer</span>
<a name="l00120"></a>00120 <span class="comment"></span>
<a name="l00121"></a>00121 <span class="comment">  void myCallback( int id ) // our code that will get called by the timer every 250 ms.</span>
<a name="l00122"></a>00122 <span class="comment">  {</span>
<a name="l00123"></a>00123 <span class="comment">    // do something here</span>
<a name="l00124"></a>00124 <span class="comment">  }</span>
<a name="l00125"></a>00125 <span class="comment">  \endcode</span>
<a name="l00126"></a>00126 <span class="comment">*/</span>
<a name="l00127"></a><a class="code" href="group___timer.html#g0c6906dbdb6527345121141fb3153744">00127</a> <span class="keywordtype">void</span> <a class="code" href="group___timer.html#g0c6906dbdb6527345121141fb3153744" title="Initializes a new timer structure.">Timer_InitializeEntry</a>( TimerEntry* timerEntry, <span class="keywordtype">void</span> (*timerCallback)( <span class="keywordtype">int</span> <span class="keywordtype">id</span> ), <span class="keywordtype">int</span> <span class="keywordtype">id</span>, <span class="keywordtype">int</span> timeMs, <span class="keywordtype">bool</span> repeat )
<a name="l00128"></a>00128 {
<a name="l00129"></a>00129   <span class="keywordtype">int</span> time = timeMs * TIMER_CYCLES_PER_MS;
<a name="l00130"></a>00130 
<a name="l00131"></a>00131   <span class="comment">// Set the details into the free dude</span>
<a name="l00132"></a>00132   timerEntry-&gt;callback = timerCallback;
<a name="l00133"></a>00133   timerEntry-&gt;id = id;
<a name="l00134"></a>00134   timerEntry-&gt;timeCurrent = 0;
<a name="l00135"></a>00135   timerEntry-&gt;timeInitial = time;
<a name="l00136"></a>00136   timerEntry-&gt;repeat = repeat;
<a name="l00137"></a>00137   timerEntry-&gt;next = NULL;
<a name="l00138"></a>00138 }
<a name="l00139"></a>00139 <span class="comment"></span>
<a name="l00140"></a>00140 <span class="comment">/**</span>
<a name="l00141"></a>00141 <span class="comment">  Sets a given TimerEntry to run.</span>
<a name="l00142"></a>00142 <span class="comment">  This routine adds the entry to the running queue and then decides if it needs</span>
<a name="l00143"></a>00143 <span class="comment">  to start the timer (if it's not running) or alter the timer's clock for a shorter</span>
<a name="l00144"></a>00144 <span class="comment">  period.</span>
<a name="l00145"></a>00145 <span class="comment">  @param timerEntry pointer to the FastTimerEntry to be run. </span>
<a name="l00146"></a>00146 <span class="comment">  */</span>
<a name="l00147"></a><a class="code" href="group___timer.html#g7397510285b17f629445eed71855c2c3">00147</a> <span class="keywordtype">int</span> <a class="code" href="group___timer.html#g7397510285b17f629445eed71855c2c3" title="Sets a given TimerEntry to run.">Timer_Set</a>( TimerEntry* timerEntry )
<a name="l00148"></a>00148 {
<a name="l00149"></a>00149   <span class="comment">// this could be a lot smarter - for example, modifying the current period?</span>
<a name="l00150"></a>00150   <span class="keywordflow">if</span> ( !Timer.servicing ) 
<a name="l00151"></a>00151     <a class="code" href="group___tasks.html#gd02e088c48f69fd07cf3157bcceb01b7" title="Specify that a task is entering a period during which it should not be interrupted...">TaskEnterCritical</a>();
<a name="l00152"></a>00152 
<a name="l00153"></a>00153   <span class="keywordflow">if</span> ( !Timer.running )
<a name="l00154"></a>00154   {
<a name="l00155"></a>00155     <a class="code" href="group___timer.html#g0ba988a1ac434ac70c17dfc239644dfe" title="Controls the active state of the Timer subsystem.">Timer_SetActive</a>( <span class="keyword">true</span> );
<a name="l00156"></a>00156     Timer_SetTimeTarget( timerEntry-&gt;timeInitial );
<a name="l00157"></a>00157     Timer_Enable();
<a name="l00158"></a>00158   }  
<a name="l00159"></a>00159 
<a name="l00160"></a>00160   <span class="comment">// Calculate how long remaining</span>
<a name="l00161"></a>00161   <span class="keywordtype">int</span> target = Timer_GetTimeTarget();
<a name="l00162"></a>00162   <span class="keywordtype">int</span> timeCurrent = Timer_GetTime();
<a name="l00163"></a>00163   <span class="keywordtype">int</span> remaining = target - timeCurrent;
<a name="l00164"></a>00164 
<a name="l00165"></a>00165   <span class="comment">// Get the entry ready to roll</span>
<a name="l00166"></a>00166   timerEntry-&gt;timeCurrent = timerEntry-&gt;timeInitial;
<a name="l00167"></a>00167 
<a name="l00168"></a>00168   <span class="comment">// Add entry</span>
<a name="l00169"></a>00169   TimerEntry* first = Timer.first;
<a name="l00170"></a>00170   Timer.first = timerEntry;
<a name="l00171"></a>00171   timerEntry-&gt;next = first;
<a name="l00172"></a>00172 
<a name="l00173"></a>00173   <span class="comment">// Are we actually servicing an interupt right now?</span>
<a name="l00174"></a>00174   <span class="keywordflow">if</span> ( !Timer.servicing )
<a name="l00175"></a>00175   {
<a name="l00176"></a>00176     <span class="comment">// No - so does the time requested by this new timer make the time need to come earlier?</span>
<a name="l00177"></a>00177     <span class="keywordflow">if</span> ( timerEntry-&gt;timeCurrent &lt; ( remaining - TIMER_MARGIN ) )
<a name="l00178"></a>00178     {
<a name="l00179"></a>00179       <span class="comment">// Damn it!  Reschedule the next callback</span>
<a name="l00180"></a>00180       Timer_SetTimeTarget( target - ( remaining - timerEntry-&gt;timeCurrent ));
<a name="l00181"></a>00181     }
<a name="l00182"></a>00182     <span class="keywordflow">else</span>
<a name="l00183"></a>00183     {
<a name="l00184"></a>00184       <span class="comment">// pretend that the existing time has been with us for the whole slice so that when the </span>
<a name="l00185"></a>00185       <span class="comment">// IRQ happens it credits the correct (reduced) time.</span>
<a name="l00186"></a>00186       timerEntry-&gt;timeCurrent += timeCurrent;
<a name="l00187"></a>00187     }
<a name="l00188"></a>00188   }
<a name="l00189"></a>00189   <span class="keywordflow">else</span>
<a name="l00190"></a>00190   {
<a name="l00191"></a>00191     <span class="comment">// Yep... we're servicing something right now</span>
<a name="l00192"></a>00192 
<a name="l00193"></a>00193     <span class="comment">// Make sure the previous pointer is OK.  This comes up if we were servicing the first item</span>
<a name="l00194"></a>00194     <span class="comment">// and it subsequently wants to delete itself, it would need to alter the next pointer of the </span>
<a name="l00195"></a>00195     <span class="comment">// the new head... err... kind of a pain, this</span>
<a name="l00196"></a>00196     <span class="keywordflow">if</span> ( Timer.previous == NULL )
<a name="l00197"></a>00197       Timer.previous = timerEntry;
<a name="l00198"></a>00198 
<a name="l00199"></a>00199     <span class="comment">// Need to make sure that if this new time is the lowest yet, that the IRQ routine </span>
<a name="l00200"></a>00200     <span class="comment">// knows that.  Since we added this entry onto the beginning of the list, the IRQ</span>
<a name="l00201"></a>00201     <span class="comment">// won't look at it again</span>
<a name="l00202"></a>00202     <span class="keywordflow">if</span> ( Timer.nextTime == -1 || Timer.nextTime &gt; timerEntry-&gt;timeCurrent )
<a name="l00203"></a>00203         Timer.nextTime = timerEntry-&gt;timeCurrent;
<a name="l00204"></a>00204   }
<a name="l00205"></a>00205 
<a name="l00206"></a>00206   <span class="keywordflow">if</span> ( !Timer.servicing ) 
<a name="l00207"></a>00207     <a class="code" href="group___tasks.html#g0911fd273992ff4dec66d096a9dc3257" title="Specify that a task is exiting a critical period, in response to TaskEnterCritical()...">TaskExitCritical</a>();
<a name="l00208"></a>00208 
<a name="l00209"></a>00209   <span class="keywordflow">return</span> <a class="code" href="group___error.html#gaa42bc036fbba18487ae9a15cd1f2f94" title="All&amp;#39;s well here.">CONTROLLER_OK</a>;
<a name="l00210"></a>00210 }
<a name="l00211"></a>00211 <span class="comment"></span>
<a name="l00212"></a>00212 <span class="comment">/** </span>
<a name="l00213"></a>00213 <span class="comment">  Cancel a timer event.</span>
<a name="l00214"></a>00214 <span class="comment">  @param timerEntry The entry to be removed.</span>
<a name="l00215"></a>00215 <span class="comment">  @return 0 on success.</span>
<a name="l00216"></a>00216 <span class="comment">  @see Timer_Set</span>
<a name="l00217"></a>00217 <span class="comment">*/</span>
<a name="l00218"></a><a class="code" href="group___timer.html#ge0bc40447f95c2309192ececf1fdee59">00218</a> <span class="keywordtype">int</span> <a class="code" href="group___timer.html#ge0bc40447f95c2309192ececf1fdee59" title="Cancel a timer event.">Timer_Cancel</a>( TimerEntry* timerEntry )
<a name="l00219"></a>00219 {
<a name="l00220"></a>00220   <span class="keywordflow">if</span> ( !Timer.servicing ) 
<a name="l00221"></a>00221     <a class="code" href="group___tasks.html#gd02e088c48f69fd07cf3157bcceb01b7" title="Specify that a task is entering a period during which it should not be interrupted...">TaskEnterCritical</a>();
<a name="l00222"></a>00222 
<a name="l00223"></a>00223   <span class="comment">// Look through the running list - clobber the entry</span>
<a name="l00224"></a>00224   TimerEntry* te = Timer.first;
<a name="l00225"></a>00225   TimerEntry* previousEntry = NULL;
<a name="l00226"></a>00226   <span class="keywordflow">while</span> ( te != NULL )
<a name="l00227"></a>00227   {
<a name="l00228"></a>00228     <span class="comment">// check for the requested entry</span>
<a name="l00229"></a>00229     <span class="keywordflow">if</span> ( te == timerEntry )
<a name="l00230"></a>00230     {
<a name="l00231"></a>00231       <span class="comment">// remove the entry from the list</span>
<a name="l00232"></a>00232       <span class="keywordflow">if</span> ( te == Timer.first )
<a name="l00233"></a>00233         Timer.first = te-&gt;next;
<a name="l00234"></a>00234       <span class="keywordflow">else</span>
<a name="l00235"></a>00235         previousEntry-&gt;next = te-&gt;next;
<a name="l00236"></a>00236       
<a name="l00237"></a>00237       <span class="comment">// make sure the in-IRQ pointers are all OK</span>
<a name="l00238"></a>00238       <span class="keywordflow">if</span> ( Timer.servicing )
<a name="l00239"></a>00239       {
<a name="l00240"></a>00240         <span class="keywordflow">if</span> ( Timer.previous == timerEntry )
<a name="l00241"></a>00241           Timer.previous = previousEntry;
<a name="l00242"></a>00242         <span class="keywordflow">if</span> ( Timer.next == timerEntry )
<a name="l00243"></a>00243           Timer.next = te-&gt;next;
<a name="l00244"></a>00244       }
<a name="l00245"></a>00245 
<a name="l00246"></a>00246       <span class="comment">// update the pointers - leave previous where it is</span>
<a name="l00247"></a>00247       te = te-&gt;next;
<a name="l00248"></a>00248     }
<a name="l00249"></a>00249     <span class="keywordflow">else</span>
<a name="l00250"></a>00250     {
<a name="l00251"></a>00251       previousEntry = te;
<a name="l00252"></a>00252       te = te-&gt;next;
<a name="l00253"></a>00253     }
<a name="l00254"></a>00254   }
<a name="l00255"></a>00255 
<a name="l00256"></a>00256   <span class="keywordflow">if</span> ( !Timer.servicing ) 
<a name="l00257"></a>00257     <a class="code" href="group___tasks.html#g0911fd273992ff4dec66d096a9dc3257" title="Specify that a task is exiting a critical period, in response to TaskEnterCritical()...">TaskExitCritical</a>();
<a name="l00258"></a>00258 
<a name="l00259"></a>00259   <span class="keywordflow">return</span> <a class="code" href="group___error.html#gaa42bc036fbba18487ae9a15cd1f2f94" title="All&amp;#39;s well here.">CONTROLLER_OK</a>;
<a name="l00260"></a>00260 }
<a name="l00261"></a>00261 <span class="comment"></span>
<a name="l00262"></a>00262 <span class="comment">/** @}</span>
<a name="l00263"></a>00263 <span class="comment">*/</span>
<a name="l00264"></a>00264 
<a name="l00265"></a>00265 <span class="comment">//</span>
<a name="l00266"></a>00266 <span class="comment">// INTERNAL</span>
<a name="l00267"></a>00267 <span class="comment">//</span>
<a name="l00268"></a>00268 
<a name="l00269"></a>00269 
<a name="l00270"></a>00270 <span class="keywordtype">int</span> Timer_GetCount()
<a name="l00271"></a>00271 {
<a name="l00272"></a>00272   <span class="keywordtype">int</span> count;
<a name="l00273"></a>00273   <a class="code" href="group___tasks.html#gd02e088c48f69fd07cf3157bcceb01b7" title="Specify that a task is entering a period during which it should not be interrupted...">TaskEnterCritical</a>();
<a name="l00274"></a>00274   count = Timer.count;
<a name="l00275"></a>00275   Timer.count = 0;
<a name="l00276"></a>00276   <a class="code" href="group___tasks.html#g0911fd273992ff4dec66d096a9dc3257" title="Specify that a task is exiting a critical period, in response to TaskEnterCritical()...">TaskExitCritical</a>();
<a name="l00277"></a>00277   <span class="keywordflow">return</span> count;
<a name="l00278"></a>00278 }
<a name="l00279"></a>00279 
<a name="l00280"></a>00280 <span class="comment">// Enable the timer.  Disable is performed by the ISR when timer is at an end</span>
<a name="l00281"></a>00281 <span class="keywordtype">void</span> Timer_Enable( )
<a name="l00282"></a>00282 {
<a name="l00283"></a>00283   <span class="comment">// Enable the device</span>
<a name="l00284"></a>00284   <span class="comment">// AT91C_BASE_TC0-&gt;TC_CCR = AT91C_TC_SWTRG;</span>
<a name="l00285"></a>00285   AT91C_BASE_TC0-&gt;TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
<a name="l00286"></a>00286   Timer.running = <span class="keyword">true</span>;
<a name="l00287"></a>00287 }
<a name="l00288"></a>00288 
<a name="l00289"></a>00289 <span class="keywordtype">int</span> Timer_GetTimeTarget( )
<a name="l00290"></a>00290 {
<a name="l00291"></a>00291   <span class="keywordflow">return</span> AT91C_BASE_TC0-&gt;TC_RC;
<a name="l00292"></a>00292 }
<a name="l00293"></a>00293 
<a name="l00294"></a>00294 <span class="keywordtype">int</span> Timer_GetTime( )
<a name="l00295"></a>00295 {
<a name="l00296"></a>00296   <span class="keywordflow">return</span> AT91C_BASE_TC0-&gt;TC_CV;
<a name="l00297"></a>00297 }
<a name="l00298"></a>00298 
<a name="l00299"></a>00299 <span class="keywordtype">void</span> Timer_SetTimeTarget( <span class="keywordtype">int</span> target )
<a name="l00300"></a>00300 {
<a name="l00301"></a>00301   AT91C_BASE_TC0-&gt;TC_RC = ( target &lt; 0xFFFF ) ? target : 0xFFFF;
<a name="l00302"></a>00302 }
<a name="l00303"></a>00303 
<a name="l00304"></a>00304 <span class="keywordtype">int</span> Timer_Init()
<a name="l00305"></a>00305 {
<a name="l00306"></a>00306   Timer.first = NULL;
<a name="l00307"></a>00307 
<a name="l00308"></a>00308   Timer.count = 0;
<a name="l00309"></a>00309   Timer.jitterTotal = 0;
<a name="l00310"></a>00310   Timer.jitterMax = 0;  
<a name="l00311"></a>00311   Timer.jitterMaxAllDay = 0;
<a name="l00312"></a>00312 
<a name="l00313"></a>00313   Timer.running = <span class="keyword">false</span>;
<a name="l00314"></a>00314   Timer.servicing = <span class="keyword">false</span>;
<a name="l00315"></a>00315 
<a name="l00316"></a>00316   <span class="comment">// Configure TC by enabling PWM clock</span>
<a name="l00317"></a>00317   AT91C_BASE_PMC-&gt;PMC_PCER = 1 &lt;&lt; AT91C_ID_TC0;
<a name="l00318"></a>00318                                     
<a name="l00319"></a>00319   <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> mask ;
<a name="l00320"></a>00320   mask = 0x1 &lt;&lt; AT91C_ID_TC0;
<a name="l00321"></a>00321    
<a name="l00322"></a>00322   <span class="comment">/* Disable the interrupt on the interrupt controller */</span>
<a name="l00323"></a>00323   AT91C_BASE_AIC-&gt;AIC_IDCR = mask;
<a name="l00324"></a>00324 
<a name="l00325"></a>00325   <span class="comment">/* Save the interrupt handler routine pointer */</span>  
<a name="l00326"></a>00326   AT91C_BASE_AIC-&gt;AIC_SVR[ AT91C_ID_TC0 ] = (<span class="keywordtype">unsigned</span> int)Timer_Isr;
<a name="l00327"></a>00327 
<a name="l00328"></a>00328   <span class="comment">/* Store the Source Mode Register */</span>
<a name="l00329"></a>00329   <span class="comment">// 4 PRIORITY is random</span>
<a name="l00330"></a>00330   AT91C_BASE_AIC-&gt;AIC_SMR[ AT91C_ID_TC0 ] = AT91C_AIC_SRCTYPE_INT_HIGH_LEVEL | 4  ;
<a name="l00331"></a>00331   <span class="comment">/* Clear the interrupt on the interrupt controller */</span>
<a name="l00332"></a>00332   AT91C_BASE_AIC-&gt;AIC_ICCR = mask ;
<a name="l00333"></a>00333 
<a name="l00334"></a>00334   <span class="comment">// Set the timer up.  We want just the basics, except when the timer compares </span>
<a name="l00335"></a>00335   <span class="comment">// with RC, retrigger</span>
<a name="l00336"></a>00336   <span class="comment">//</span>
<a name="l00337"></a>00337   <span class="comment">// MCK is 47923200</span>
<a name="l00338"></a>00338   <span class="comment">// DIV1: A tick MCK/2 times a second</span>
<a name="l00339"></a>00339   <span class="comment">// This makes every tick every 41.73344ns</span>
<a name="l00340"></a>00340   <span class="comment">// DIV2: A tick MCK/8 times a second</span>
<a name="l00341"></a>00341   <span class="comment">// This makes every tick every 167ns</span>
<a name="l00342"></a>00342   <span class="comment">// DIV3: A tick MCK/32 times a second</span>
<a name="l00343"></a>00343   <span class="comment">// This makes every tick every 668ns  </span>
<a name="l00344"></a>00344   <span class="comment">// DIV4: A tick MCK/128 times a second</span>
<a name="l00345"></a>00345   <span class="comment">// This makes every tick every 2.671us</span>
<a name="l00346"></a>00346   <span class="comment">// DIV5: A tick MCK/1024 times a second</span>
<a name="l00347"></a>00347   <span class="comment">// This makes every tick every 21.368us</span>
<a name="l00348"></a>00348   <span class="comment">// CPCTRG makes the RC event reset the counter and trigger it to restart</span>
<a name="l00349"></a>00349   AT91C_BASE_TC0-&gt;TC_CMR = AT91C_TC_CLKS_TIMER_DIV5_CLOCK | AT91C_TC_CPCTRG;
<a name="l00350"></a>00350                    
<a name="l00351"></a>00351   <span class="comment">// Only really interested in interrupts when the RC happens</span>
<a name="l00352"></a>00352   AT91C_BASE_TC0-&gt;TC_IDR = 0xFF; 
<a name="l00353"></a>00353   AT91C_BASE_TC0-&gt;TC_IER = AT91C_TC_CPCS; 
<a name="l00354"></a>00354 
<a name="l00355"></a>00355   <span class="comment">// load the RC value with something</span>
<a name="l00356"></a>00356   AT91C_BASE_TC0-&gt;TC_RC = 0xFFFF;
<a name="l00357"></a>00357 
<a name="l00358"></a>00358   <span class="comment">// Enable the interrupt</span>
<a name="l00359"></a>00359   AT91C_BASE_AIC-&gt;AIC_IECR = mask;
<a name="l00360"></a>00360 
<a name="l00361"></a>00361   <span class="keywordflow">return</span> <a class="code" href="group___error.html#gaa42bc036fbba18487ae9a15cd1f2f94" title="All&amp;#39;s well here.">CONTROLLER_OK</a>;
<a name="l00362"></a>00362 }
<a name="l00363"></a>00363 
<a name="l00364"></a>00364 <span class="keywordtype">int</span> Timer_Deinit()
<a name="l00365"></a>00365 {
<a name="l00366"></a>00366   <span class="keywordflow">return</span> <a class="code" href="group___error.html#gaa42bc036fbba18487ae9a15cd1f2f94" title="All&amp;#39;s well here.">CONTROLLER_OK</a>;
<a name="l00367"></a>00367 }
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  <p class="footer">The Make Controller Kit is an open source project maintained by <a href="http://www.makingthings.com">MakingThings</a>.<br />
    MakingThings code is released under the <a href="http://www.apache.org/licenses/LICENSE-2.0.html" target="_blank">Apache 2.0 license</a>.<br />
    Bug tracker, development wiki and status can be found at <a href="http://dev.makingthings.com">http://dev.makingthings.com</a>.<br />
		This document was last updated on 5 Dec 2007.
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